(01-23) 15:32 PST San Francisco -- Most arrests do not involve people who are on probation or parole, according to a 3 1/2-year study examining millions of criminal records in four cities including San Francisco - an outcome that challenges the assumption that convicted criminals are driving crime rates, backers of the report said.

The analysis by the nonprofit, nonpartisan Council of State Governments found that people under parole or probation supervision accounted for just one-fifth of all arrests made in San Francisco, Sacramento, Los Angeles and Redlands between Jan. 1, 2008, and June 30, 2011 - and were responsible for only 1 out of every 6 arrests for a violent crime. The organization helps state governments shape policy in part by conducting research and hosting conferences.

The study also determined that some scientific risk-assessment tools, such as those used already by the state and San Francisco, are good predictors of future criminal behavior. Risk assessments gauge a person's likelihood of committing another crime, and quantify factors such as joblessness, family instability and drug use that could lead to such behavior.

For example, the analysis determined that almost no felons released under the state's short-lived and controversial "non-revokable parole" program - which exempted low-risk offenders released from state prison from parole - were rearrested.

The findings, said San Francisco District Attorney George Gascón, "really push back on the concept that people under supervision are more likely to commit crimes than other people." It also challenges the assumption that Gov. Jerry Brown's realignment plan, which in October 2011 began shifting the responsibility for jailing and supervising many felons from state to local agencies, is boosting crime rates, he said.

Gascón requested the study, along with the police chiefs of the other participating cities, when he was San Francisco's police chief.

The study concludes that to reduce crime, law enforcement officials need to spend more time focusing on the nearly 80 percent of people who are not already under supervision, and better target the small subset of people on probation and parole who are disproportionately breaking the law, largely for drug-related crimes.

It recommends that law enforcement use risk-assessment tools, improve data collection and analysis, increase coordination among law enforcement agencies, and provide "targeted, evidence-based supervision and treatment" to high-risk offenders in order to keep them out of jails and prison.

S.F. activity

San Francisco already does most of those things, said Probation Chief Wendy Still - and was the only city in the study with a highly accurate risk-assessment system. San Francisco also had the lowest percentage of people on probation and parole, and the biggest drop in arrest rates over the study period.

"I couldn't be more pleased," she said.

Still said San Francisco has worked to expand its use of these risk-assessment systems to also inform sentencing and supervision decisions. Those changes have led San Francisco to focus most of its efforts on the most high-risk offenders, and have made a huge difference, she said.

"We have changed our supervision strategy from supervising by type of case to by risk level," she said. "And it's remarkable - during the first year of realignment, 60 percent of (people being released from state prison) were compliant with the terms of their supervision, as compared to (state) parole where they had a 70 percent failure rate."

Study's impact

More generally, the study will make it easier to track the true implications of realignment in the future - and for police to better target crime-prevention strategies, said Robert Coombs, communications director at the Council of State Governments' Justice Center. In the past, the only information that law enforcement and policymakers had available was the failure rate of parolees and probationers, he said.

"We've always known how much probationers and parolees contribute to crime, but we didn't know ... what proportion of crime they make up," he said. "This is really, really important, because it contributes in a significant way to how we respond."

Gascón agreed, saying the study should inform how police, prosecutors, courts and probation officials all approach their jobs. For example, police who are trying to prevent and investigate crime should be focusing more on high-crime areas and types of crime than simply targeting people on probation or parole, he said.

"And I think efforts placed on supervision need to be targeted toward prevention, and enhancement services, rather than trying to find violations and re-incarcerate."

For prosecutors, he said, "The final outcome should not be viewed as a conviction, sending someone to jail, but to how they will be re-integrated into the community afterward. It's important because most people will be coming out."